1. Field of the Invention
This invention relates generally to a power supply for an electric precipitator which includes a d-c voltage source and a pulsed a-c voltage source coupled to the high-voltage electrodes of the precipitator.
2. Description of the Prior Art
Power supplies of the foregoing type are known in the art. See, for example, the journal "Staub", 1976, pages 19 through 26. In the power supply described in this publication, high-votage a-c pulses and a d-c voltage are fed to separate electrodes of a precipitator. However, it is also possible to superimpose both voltages upon each other by decoupling the voltage sources from each other by means of a transformer or capacitor. See German Offenlegungsschrift No. 2, 341, 541. The supplemental use of a pulsed a-c voltage increases, in both cases, the degree of ionization of the gas to be purified and thereby improves the precipitation effect.
Power supplies of the aforesaid type have only been slowly introduced into practice and the reason for this is the high cost of generating pulsed a-c voltages with a high pulse repetition frequency at the voltages and power levels required, particularly if the electrical data are to be variable. Considering the large number of equipments required, ordinary inverters are much too expensive for this purpose.